Evaluation of antioxidant andanti-inflammatory activities of Hypericum tomentosum L.leaves extracts

Abstract

This study aims to evaluate the anti-inflammatory and antioxidant activities of aqueous (Aq.E) and methanolic (Met.E) extracts of Hypericum tomentosum leaves.The quantitative assessment of phenolic compounds showed that Met.E extract of this plant contains the highest amount of polyphenols,flavonoids and tannins compared to Aq.E.HPLC analysis showed the presence of many flavonoids and phenolic acids, quercetrin and epicatechin recorded the highest amount among flavonoids,while quinic acid and chlorogenic acid had the highest concentration among the phenolic acids.The antioxidant activity of Aq.E and Met.E was estimated in vitro by determining the scavenging activity of DPPH•,OH•and H2O2. The results show that both Aq.E and Met.E inhibited DPPH•with IC50 values of 9.32 and 5.85 μg/mL, respectively and they inhibited OH• with IC50 equal to 338.8 and 377.6 µg/mL and the values of IC50 with H2O2 were 3.13 and 2.07 µg/mL,respectively. Both extracts also showed a great ability to reduce ferric ion and inhibit lipid oxidation, through the protective effect against the lysis of red blood cells caused by radicals attack and through prevention of linoleic acid oxidation by inhibition levels of 77.48% with Aq.E and 29.43 % with Met.E, while the ability of the two extracts to chelate ferrous ions was weak. The results of anti-inflammatory activity demonstrated that treating mice with 1 mg/mL of Aq.E and Met.E extracts significantly(p<0.001) inhibited neutrophils migration by 38.53% and 47.5%, respectively. Topical application of both Aq.E and Met.E to mice, in the ear edema model induced by croton oil,reduced edema by 68.75% and 67%,respectively . While orally treatment of mice with a concentration of 200 mg/kg and 400 mg/kg of both extracts showed a weak effectiveness in reducing paw edema induced by carrageenan. The same concentrations proved an ability to inhibit pain caused by acetic acid. Both extracts showed anti-inflammatory activity through tests evaluating the effects of the studied extracts on human neutrophils functions. They exerted a big inhibition and dose- dependent manner elastase and myeloperoxidase activities.The two extracts were shown to be able to inhibit significantly (p<0.05) bactericidal activity exerted on Escherichia coli.However,in assay of cellular phagocytosis of Candida albicans cells by human neutrophils, the studied extracts showed slight and non-ignificant inhibition of phagocytosis.